Sunitinib base is having the chemical name N-[2-(diethylamino)ethyl]-5-[(5-fluoro-1,2-dihydro-2-oxo-3H-indol-3-ylidene)methyl-2,4-dimethyl-1H-pyrrole-3-carboxamide is also known as SU11248 and similar pyrrole derivatives are first disclosed in WO 0160814 (2001).
In the above said patent, the manufacturing process for Sunitinib is described as shown in Scheme-1 below.

According to the above patent:
Tertiary butylacetoacetate (II) and ethyl acetatoacetate (III) were reacted by a well-known Knorr-pyrrole synthesis (Org. Synth., Coll. Vol. II, p 202) using sodium nitrite, zinc and acetic acid to get the diester pyrrole derivative (IV).
Later it is selectively decarboxylated in the presence of aqueous HCl to get half-ester pyrrole derivative (V).
The compound (V) is then formylated by a known synthetic methodology using DMF-POCl3 complex to get the formylated ester derivative (VI).
The half-ester derivative (VI) is selectively hydrolyzed to get a carboxylic acid derivative (VII).
The carboxylic acid derivative (VII) is then selectively converted to amide (IX) using 2-(Diethylamino ethylamine (VIII) in the presence of 1-(3-dimethylaminopropyl-3-ethylcarbodiimide HCl.
Finally the formyl derivative (IX) is coupled with 5-Fluoro-2-oxindole (X) by Knoevenagel method using pyrrolidine as a catalyst to get Sunitinib base (I). The product was characterized by 1H NMR and Mass spectral analysis.
However, the information regarding the solid state characteristics like powder XRD, DSC, IR data or specific crystal forms of N-[2-(diethylamino)ethyl]-5-[(5-fluoro-1,2-dihydro-2-oxo-3H-indol-3-ylidene)methyl-2,4-dimethyl-1H-pyrrole-3-carboxamide-Sunitinib base (I) are not disclosed in the above mentioned patent (WO 01/60814).
A study of the solid state properties of this important anti-cancer entity will be extremely useful from the therapeutic and pharmaceutical point of view. Hence we have taken up a detailed investigation of these aspects.
In the current scenario demanding high quality standards of drug substances and drug products, physical characteristics (like powdered XRD, DSC and IR) play an important role in pharmaceutical industry.
Due to poor solubility nature of Sunitinib base in ethanol or methanol, very large volumes of solvent is required to crystallize Sunitinib base. Hence a better process for preparation of high purity of Sunitinib base directly obtainable from the reaction mixture is highly desirable. In that direction a detailed study was taken-up.
During our experimental work on the reactivity of Sunitinib base in various solvents, surprisingly a wide variety of novel polymorphic forms of the said base were discovered. These novel forms are found to be stable, reproducible, and suitable for conversion to pharmaceutically acceptable salt preparations. Also, surprisingly the condensation of formyl derivative (IX) with 5-Fluoro-2-oxindole (X) is found to proceed even in the absence of a catalyst.
However, certain basic and acidic catalysts are found to hasten the reaction and improve the yields. These catalysts include inorganic bases like ammonia, alkali metal or alkaline earth hydroxides, carbonates, phosphates, bicarbonates and alkali metal hydroxides viz sodium hydroxide, potassium hydroxide or alkaline earth metal hydroxides viz calcium hydroxide, magnesium hydroxide or barium hydroxide, methanolic or ethanolic ammonia, quaternary ammonium compounds like tetra butyl ammonium hydroxide, benzyltrimethyl ammonium hydroxide, silica gel, sodium acetate, ammonium acetate or Lewis acids like Boron trifluoride etherate and organic bases like piperidine, piperazine, pyrrolidine, sodium ethoxide, sodium methoxide, para toluene sulfonic acid (PTSA) are found to hasten the reaction and improve the yields.